The interaction of a specific viral antigen and a class 1 MHC (major histocompatibility complex) polypeptide on the cell surface has been shown to be an important target for cytotoxic T lymphocytes (CTL). This interaction effects the pathogenesis of a variety of viral infections and influences the clinical manifestations as well as the outcome of these diseases. In contrast to other viruses, the adenoviruses (Ad) effect the MHC products in unique ways in that the Ads have evolved several mechanisms for decreasing the amount of the class 1 MHC proteins on the cell surface. For example, a specific 19kd Ad glycoprotein (e19) from early transcription region 3 (E3) binds to class 1 MHC products primarily in the endoplasmic reticulum ER), where the e19, fixed in the organelle membrane,inhibits the transport of MHC products to the cell surface. These observations have been made primarily in tissue culture using human Ads. This proposal extends these studies to an in vivo model in which the effect of these unique viral-host interactions on the pathogenesis of disease can be studied. Mice will be utilized because of the extensive structural and genetic information already available on the murine class 1 mouse MHC genes (H2) and their polypeptide products. The effect of H-2 mutations on murine mortality, organ pathology, and the amount of virus in affected tissues will be measured after infection with the mouse adenovirus, AdFL. Our initial results suggest an alteration of viral virulence in mice which carry in mutations their H-2Kb genes. These studies will be expanded to include other H-2Kb as well as H-2Db mutations. The AdFL E3 region will be cloned and sequenced to determine the structure of the various polypeptides coded within this domain. The structure of the e19 viral glycoprotein will be determined as part of these studies and the various domains that potentially interact with the H-2 MHC, as well as those responsible for anchoring the e19 in the ER will be defined. Deletion and site specific mutants in e19 will be constructed to test the function of these various regions and the role of the N-linked glycosylation sites in determining pathogenicity of the AdFL in mice. The sites on the H-2Kb molecule that interact with the e19 polypeptide will be determined through the use of several series of H-2 mutants. The production of cytotoxic T lymphocytes in various mutant mouse strains will be correlated with in vivo pathogenesis as well as with the ability of each of the studied H-2Kb mutants to interact with the e19 viral glycoprotein.